Products derived from the isoindole of the general formula: ##STR3## which exhibit opium activity, had been described in U.S. Pat. No. 4,042,707.
These products exhibit no activity towards substance P.
In spite of the research carried out and in spite of the interest created [M. R. Hanley, TINS, (5) 139 (1982)], practically no product had been discovered so far which acts specifically on substance P and which has a nonpeptide structure; accordingly, the isoindole derivatives of general formula (I) are of great interest.